"The watertight-bulkhead technology of Chinese junks", submitted cooperatively by Jiaocheng...

China's period of slave society disintegrated during the Spring and Autumn Period, sometime after 700 BC. Progress in productivity brought about drastic changes in social life and politics. Different classes with different schools of thought were unprecedentedly active, giving rise to a situation of ``many schools of thought contending with each other," and promoting science and culture. The major schools were those of the Confucianists, Moists Taoists Legalists, military strategists, Logicians, and Political Strategists. Among them, the works and doctrines of such famous thinkers and military strategists as Lao Zi, Sun Zi and Sun Wu are still widely circulated in the world today.

Lao Zi, founder of Taoism, lived during the Spring and Autumn Period. Whether he was the true author of the book Dao De Jing (The Book of Virtue) has long been in dispute. However, the majority of scholars tend to believe that the book reflects his thinking. Lao Zi used the concept of the "Dao" (Way) to explain all changes in the universe, and put forward dialectical ideas such as "Dao gives rise to one, one gives rise to two, two gives rise to three and three gives rise to all other things", "All things under Heaven came from something which in turn came from nothing" and "Good fortune lies within bad, bad fortune lurks within good". In aesthetics, he advocated the concepts of "Great sound is rarely heard" and "Great images have no forms". The theory of Lao Zi exerted a great impact on the development of philosophy in China, and later scholars made use of his thinking in various ways. The Dao De Jing has been translated into many languages. Apart from its philosophical views, the moral principles standing for universal love as expressed in the following words "To honor others' aged people as we honor our own; and to be kind to others' young as we are to our own" are often quoted with approval by people today.

Confucius (551-479 BC) toured various states during the Spring and Autumn Period advocating his ideas on right conduct, in order to shore up aristocratic rule. Later he devoted his energy to teaching by opening schools and enrolling some 3,000 students. Among them, seventy-two were noted scholars who helped compile ancient books and put his teachings into the book titled The Analects. For 2,000 years, Confucianism was the dominating force in the feudal society of China, exerting a significant impact on the stability and moral principles of society. Having spread to East and Southeast Asia, his thinking became an important guiding ideology in many countries, making Confucius a world-level thinker.

Sun Wu was an outstanding military strategist in the late years of the Spring and Autumn Period, and helped Ge Lu, king of the State of Wu, to realize his ambitions. His book, The Art of War, is the earliest writing on military strategies in the world. Some of the strategies and tactics in the book are still used in military affairs and even enterprise management, commercial competition and sports competition today. The book spread to other Asian countries, and further on to distant Europe as early as the Tang Dynasty (618-907). It is said that Napoleon read The Art of War during his campaigns and Emperor William II of Germany once expressed regret that he had not read the book 20 years earlier. Now this book has been translated into a dozen languages.

Wang Chong, who lived in the early years of the Eastern Han Dynasty (25-220) was an outstanding materialist thinker in Chinese history. His Discourses Weighed in the Balance is an ancient philosophical work that illuminates plain materialist thinking. In the book, he discusses the materialist concept of nature, refutes the idea of ghosts and elaborates on "the response between Heaven and man."

During the Ming Dynasty, new idealist theories, such as what was advocated by Wang Shouren, emerged. At the same time, progressive thinkers with democratic characteristics were also produced, Li Zhi (1527-1602) being one of the most outstanding representatives in this regard. He was opposed to the deification of Confucius, arguing that it was unnecessary to consult Confucius on everything and that Confucian theory should not be adopted as the only criteria for judging right and wrong. He refuted the feudal class system, opposed feudal rites and propagated equality between men and women. His theories aroused official alarm, and consequently Li Zhi was persecuted to death.